Selective tuning device



Aug. 29, 1933.. c, HOUGH 1,924.553

SELECTIVE TUNING DEVICE Filed Jan. 21, 1931 3 Sheets-Sheet l INVENTOR CZz'mon I V. Hough.

TORNEY Aug. 29, 1933. c" w HOUGH 1,924,553

SELECTIVE TUNING DEVICE Filed Jan. 21, 1931 3 Sheets-Sheet 2 ElE-Q...E

INVENTOR G'Zz'n fan W fz ouyh ORNEY Aug. 29, 1933.

c. w. HOUGH 1,924,553

7 SELECTIVE TUNING DEVICE Filed Jan. 21. 1931 3 SheetsSheet 3 INVENTOR Q Q C/L'nfon W Houyh ORNEY Patented Aug. 29, 1933 I UNITED STATES PATENT OFFICE Wired Radio, Inc., New York,

poration of Delaware N. Y., a cor- Application January 21, 1931. Serial No. 510,082

1 Claim.

My invention pertains in general to radio tuning devices and specifically relates to a tuning device in which the circuit constants can be selectively changed by predetermined values.

One of the objects of my'invention consists in providing a selective tuning device which is extremely compact in its construction and which is simple in its operation.

Another object consists in producing a unitary construction of selective tuning device in which the circuit constants can be changed by predetermined values by a central control. knob.

A further object comprises producing a sole"- tive tuning device incorporating a wave filter system having a plurality of different capacitance values which can be selectively rendered eiiective in the tuning circuit by a unified control arrangement.

A still further object consists in providing a substantially circular construction of selective tuning device in which the selection of eff ctive values of circuit constants, as well as volume control, can be eiiected by central rotatable control means.

I accomplish the above desirable objects in a novel type of selective tuning device of unitary construction in which two co-axial control knobs are provided for the selection of predetermined values of circuit constants.

I ment of the selective tuning device of my invention.

My invention is directed to providing an extremely compact construction of selective tuning device especiallyadapted for use in conjunction with amplifying and detecting systems. The selective tuning system according to my invention comprises a unitary construction of wave filter system of a type in which the circuit constants are altered by predetermined values to change the transmission response characteristics of the system. That is, the system is selectively responsive to predetermined frequency bands. Such a tuning system is especially adapted for use in wired radio broadcasting systems in which the programs are distributed at several predetermined discrete frequencies. 1 The construction of the selective tuning devce according to my invention is oi a nature such that it may be readily incorporated in an arm: lifier and/or detector organization.

Consideration will first be given to the electrical arrangement of the selective tuning device of my invention. R er ing to Fig. 5, I provide a plurality of annular-Ly disposed contacts 4-23 inclusive. A contact sector 24 and a contact sector 25 are positioned upon a rotatable mounting member 3. The contacting sector 24 is provided with two blades, one of which is adapted to rotatabiy cn gage with any one of the contacts i? and the other of which is adapted to t t with the contacts 2023. T" e contacting sector 25 is provided with three blades which are adapted to rotatably engage witlthree sets of contacts 8 11, 12-15, and 1619, respectively. The contacts 5, 6, and 7 are connected to capacitances 2 28, and 29, respectively, while the contacts 9, 1G, and 11 are connected to capacitahces 31, and 32, respectively. Contacts 13, is, and 15 are connected to capacitances as, and 35, respectively, while contacts 17, 18, and 19 are connected to capacitances 35, 37, and 38, respectively. The contacts 21, 22, and 23 are connected, as shown, to the winding of an auto-transformer 39. Con-- tacts 4, 8, 12, 16, and 20 are not connected to any circuit but are provided as off positions for the blades of the contacting sectors 24 and 25.

The capacitances 27, 28, and 29 are of different values and are connected to primary inductance 4c electromagnetic- -ly cou ed to secondary inductance 41, while the capacitances oi), 31, and 312 are of different values and are connected to a primary inductance electromagnetically coupled to a secondary inductance 43. The capa citances 34, and are of d. rent values and are connected to a primary inductance 44 electromagnetically coupled to a se cndary inductance i5, while the capacitances S6, 37, and 38 are of different values and are connected to a resistance The secondary inductances s1, 413, and 45 are, on one side, commonly connected to the output terminal 48 to the contacting sector 25. The secondary inductance ell is also connected to the primary inductance while the secondary inductance connected to the primary inductance is. The inducance 45. is connected to the resistance 46 and n in to the output terminal 47. The auto-transformer inductance 39 is connected to the primary inductance 40 and also through capacitance 49 to the input terminal 50. A potentiometer resistance 53 is connetced from a point between the capacitance 49 and auto-transformer inductance 39 through a capacitance 52 to an input terminal 51. A movable contact 54 is provided with the resistance 53 for rendering a desired value thereof effective, and is connected to the contacting sector 24. The inductances 4041 are enclosed by a grounded electromagnetic shield 57, the inductances 4243 are enclosed by a grounded electromagnetic shield 58, and the inductances 44-45 are enclosed by a grounded electromagnetic shield 59.

The foregoing electrical organization comprises a band pass filter system in which the circuit constants can be changed by predetermined values to render the filter system effective to selective frequency bands in accordance with the principles set forth in a co-pending application of Robert D. Duncan, Jr., Serial Number 495,823, filed November 15, 1930, and entitled Filter system.

The mechanical structure of my invention will be understood by reference to Figs. 1, 2, 3, and 4. A mounting disk 1, composed of insulating material, such as a phenol condensation product, is provided with up-right spacers 2. The up-right spacers 2 support a circular member 60 upon which are annulary mounted the contacts 4 to 23 inclusive. The capacitances 27 to 38 inclusive are radially mounted upon the member 60 directly beneath their respective contacts. The contact sectors 24 and 25 are composed of a resilient metal, such as german silver, and are mounted upon the insulating rotatable mounting member 3. The mounting member 3 is rigidly secured to a hollow shaft 61 which extends through a circular insulating knob 62. A set screw 63 is provided within the knob 62 to permit proper positioning of the knob 62 upon the shaft 61. Another shaft 64 is rotatably mounted within the mounting member 60 and is secured to a movable contact 54 which engages in contact with the potentiometer resistance 53. Rotation of the shaft 64 by an insulating knob 65 will cause the contact 64 to render selecive portions of the resistance 53 effective in the circuit.

The hollow shaft 61 is free to rotate independently of the internal shaft 64.

The resistance 46 and the auto-transformer indutance 39 are suspended from the mounting member 60. The capacitances 52 and 49 are centrally mounted upon the top of the member 1.

The inductances 40 to 45 inclusive are mounted upon insulating members 66 which are suspended from the mounting member 1. These inductances are enclosed by the electro-magnetic shields 57, 58, and 59, as before stated. The shields 57, 58, and 59 are composed of a suitable metal such as brass or aluminum.

The knob 62 can be rotated to cause the contact sectors 24 and 25 to render selective values of circuit constants effective to make the filter system responsive to a selective frequency band. At the same time, the knob 65 can be adjusted to control the output volume of the filter system. It will be apparent that the co-axial arrangement of the shafts bearing the knobs 62 and 65 permits of a centralized control of the filter system. For example, the entire control can be accomplished by the use of one hand. Such an arrangement presents a distinct advancement in the construction and switching arrangement of a filter system of the type indicated. Although I have shown a preferred. embodiment of my invention, I do not wish to be limited thereto except insofar as may be pointed out in the appended claim.

What I claim as new and original and desire to secure by Letters Patent of the United States A selective tuning device comprising, a substantially circular mounting member, a plurality of contacts annularly positioned upon said mounting member, a second substantially circular mounting member, spacers interconnecting said mounting members, a plurality of inductances mounted upon said second mounting member, a plurality of capacitances connected to said contacts, a rotatable switch for engaging selected groups of said contacts to render selected values of said capacitances effective in cooperation with said inductances, a variable resistance, and a. rotatable member for said variable resistance, said member being co-axial with respect to said rotatable switch.

CLINTON W. HOUGH. 

